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About Git write access:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Before everything else, you should know how to use GIT properly.
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Luckily Git comes with excellent documentation.
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  git --help
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  man git
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shows you the available subcommands,
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  git <command> --help
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  man git-<command>
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shows information about the subcommand <command>.
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The most comprehensive manual is the website Git Reference
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http://gitref.org/
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For more information about the Git project, visit
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http://git-scm.com/
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Consult these resources whenever you have problems, they are quite exhaustive.
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You do not need a special username or password.
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All you need is to provide a ssh public key to the Git server admin.
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What follows now is a basic introduction to Git and some FFmpeg-specific
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guidelines. Read it at least once, if you are granted commit privileges to the
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FFmpeg project you are expected to be familiar with these rules.
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I. BASICS:
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==========
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0. Get GIT:
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  You can get git from http://git-scm.com/
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1. Cloning the source tree:
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    git clone git://git.ffmpeg.org/ffmpeg.git <target>
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  This will put the FFmpeg sources into the directory <target>.
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    git clone git@git.ffmpeg.org:ffmpeg.git <target>
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  This will put the FFmpeg sources into the directory <target> and let
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  you push back your changes to the remote repository.
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2. Updating the source tree to the latest revision:
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    git pull (--ff-only)
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  pulls in the latest changes from the tracked branch. The tracked branch
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  can be remote. By default the master branch tracks the branch master in
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  the remote origin.
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  Caveat: Since merge commits are forbidden at least for the initial
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          months of git --ff-only or --rebase (see below) are recommended.
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          --ff-only will fail and not create merge commits if your branch
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          has diverged (has a different history) from the tracked branch.
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2.a Rebasing your local branches:
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    git pull --rebase
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  fetches the changes from the main repository and replays your local commits
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  over it. This is required to keep all your local changes at the top of
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  FFmpeg's master tree. The master tree will reject pushes with merge commits.
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3. Adding/removing files/directories:
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    git add [-A] <filename/dirname>
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    git rm [-r] <filename/dirname>
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  GIT needs to get notified of all changes you make to your working
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  directory that makes files appear or disappear.
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  Line moves across files are automatically tracked.
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4. Showing modifications:
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    git diff <filename(s)>
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  will show all local modifications in your working directory as unified diff.
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5. Inspecting the changelog:
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    git log <filename(s)>
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  You may also use the graphical tools like gitview or gitk or the web
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  interface available at http://git.ffmpeg.org/
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6. Checking source tree status:
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    git status
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  detects all the changes you made and lists what actions will be taken in case
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  of a commit (additions, modifications, deletions, etc.).
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7. Committing:
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    git diff --check
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  to double check your changes before committing them to avoid trouble later
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  on. All experienced developers do this on each and every commit, no matter
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  how small.
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  Every one of them has been saved from looking like a fool by this many times.
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  It's very easy for stray debug output or cosmetic modifications to slip in,
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  please avoid problems through this extra level of scrutiny.
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  For cosmetics-only commits you should get (almost) empty output from
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    git diff -wb <filename(s)>
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  Also check the output of
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    git status
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  to make sure you don't have untracked files or deletions.
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    git add [-i|-p|-A] <filenames/dirnames>
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  Make sure you have told git your name and email address, e.g. by running
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    git config --global user.name "My Name"
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    git config --global user.email my@email.invalid
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  (--global to set the global configuration for all your git checkouts).
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  Git will select the changes to the files for commit. Optionally you can use
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  the interactive or the patch mode to select hunk by hunk what should be
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  added to the commit.
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    git commit
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  Git will commit the selected changes to your current local branch.
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  You will be prompted for a log message in an editor, which is either
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  set in your personal configuration file through
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    git config core.editor
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  or set by one of the following environment variables:
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  GIT_EDITOR, VISUAL or EDITOR.
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  Log messages should be concise but descriptive. Explain why you made a change,
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  what you did will be obvious from the changes themselves most of the time.
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  Saying just "bug fix" or "10l" is bad. Remember that people of varying skill
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  levels look at and educate themselves while reading through your code. Don't
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  include filenames in log messages, Git provides that information.
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  Possibly make the commit message have a terse, descriptive first line, an
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  empty line and then a full description. The first line will be used to name
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  the patch by git format-patch.
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8. Renaming/moving/copying files or contents of files:
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  Git automatically tracks such changes, making those normal commits.
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    mv/cp path/file otherpath/otherfile
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    git add [-A] .
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    git commit
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  Do not move, rename or copy files of which you are not the maintainer without
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  discussing it on the mailing list first!
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9. Reverting broken commits
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    git revert <commit>
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  git revert will generate a revert commit. This will not make the faulty
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  commit disappear from the history.
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    git reset <commit>
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  git reset will uncommit the changes till <commit> rewriting the current
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  branch history.
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    git commit --amend
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  allows to amend the last commit details quickly.
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    git rebase -i origin/master
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  will replay local commits over the main repository allowing to edit,
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  merge or remove some of them in the process.
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  Note that the reset, commit --amend and rebase rewrite history, so you
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  should use them ONLY on your local or topic branches.
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  The main repository will reject those changes.
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10. Preparing a patchset.
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    git format-patch <commit> [-o directory]
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  will generate a set of patches out of the current branch starting from
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  commit. By default the patches are created in the current directory.
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11. Sending patches for review
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    git send-email <commit list|directory>
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  will send the patches created by git format-patch or directly generates
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  them. All the email fields can be configured in the global/local
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  configuration or overridden by command line.
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12. Pushing changes to remote trees
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    git push
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  Will push the changes to the default remote (origin).
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  Git will prevent you from pushing changes if the local and remote trees are
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  out of sync. Refer to 2 and 2.a to sync the local tree.
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    git remote add <name> <url>
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  Will add additional remote with a name reference, it is useful if you want
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  to push your local branch for review on a remote host.
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    git push <remote> <refspec>
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  Will push the changes to the remote repository. Omitting refspec makes git
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  push update all the remote branches matching the local ones.
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13. Finding a specific svn revision
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  Since version 1.7.1 git supports ':/foo' syntax for specifying commits
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  based on a regular expression. see man gitrevisions
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    git show :/'as revision 23456'
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  will show the svn changeset r23456. With older git versions searching in
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  the git log output is the easiest option (especially if a pager with
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  search capabilities is used).
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  This commit can be checked out with
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    git checkout -b svn_23456 :/'as revision 23456'
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  or for git < 1.7.1 with
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    git checkout -b svn_23456 $SHA1
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  where $SHA1 is the commit SHA1 from the 'git log' output.
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Contact the project admins <git at ffmpeg dot org> if you have technical
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problems with the GIT server.